Mask Praxis is an investigation of the theories and practices behind the uses of the mask in modern drama from 1896 to 2004. The study traces the crisis in humanism through the use of idealist and materialist masks by theatre practitioners and explains how the search for a unified field was overlaid by fractured identities and a slide into dissonance. How important are the masks that people adopt on the stage for understanding their actions in society? How does the metaphorical power and perceptual ambiguity of the mask correlate with intentions of its maker and performer? What is the relationship between the mask and the face of the actor, and what does the mask do that cannot be done unaided? What are the main approaches to actor training that have used masks, and how are these training systems connected to wider belief systems? What do we learn from the act of masking about self-perception and social being, and what are the principal considerations that this gives rise to? This investigation proceeds from a consideration of major theories and practices. Chapter 1 examines mask performance theories, conventions, and typologies. Chapter 2 analyses the specificity of the mask, materials and methods, representative mask-makers and provides casebook studies on the Sartori family and the Masks for Menander Project. Chapter 3 evaluates actor-training under the mask from Copeau to Lecoq. Chapter 4 assesses the masks of idealist modernism and Chapter 5 considers the masks of materialist modernism. The final chapter is dedicated to transnational flows, multinational productions and the notion of connectivity. It brings new evidence to bear on the emergent field of masks, puppets and performing objects and sets down a major overview of the mask as a primary iconographic tool and as a liminoid instrument from which to mediate and direct the flow of power in a system.